Safety lighter with double-wheel and buffer-wheel ignition device

ABSTRACT

A safety lighter includes double rotating wheels provided on each side of a sparking wheel, with a buffer wheel between one of the double rotating wheels and the sparking wheel and received around an axle portion of the one rotating wheels. The buffer wheel hinders rotation of the rotating wheels and sparking wheel, idling freely and shielding one of the rotating wheels from a young/small user. Upon sufficient adult force downward on the buffer wheel, however, the axle and aperture surfaces will mate/grip sufficiently to allow the force on the buffer wheel to drive the rotating wheel. Also, some adults will be able to press the buffer wheel (to engage with the axle) and both of the two rotating wheels at the same time to drive the wheel set. The buffer wheel may be included in a common double-wheel lighter wheel system, with little if any change to the total axial length of the wheel assembly, and, hence, little if any change to the lighter structure other than the wheels.

TECHNICAL FIELD

The invention relates to a disposable lighter with a safety ignition device.

BACKGROUND OF THE INVENTION

The present invention relates to a disposable lighter with a safety ignition device that makes operation by an unintended user more difficult. The present invention relates more particularly to an ignition device preventing children from igniting the disposable lighter.

Simple Lighter:

Presently, many lighters available in the world, especially disposable lighters, can be easily ignited by young children and thus cause hidden dangers in property loss and personal injury. More and more countries, especially Western countries, have attached great importance to the protection of children and imposed strict measures on safety requirements for lighters. Nowadays, both the U.S. government and U.S. Consumer Product Safety Commission demand a safety device in every cigarette lighter, including the disposable lighter, in order to prevent accidental ignition or ignition by a child.

A “simple lighter,” without a safety ignition unit, generally includes a body and a head, on which there is a nozzle, a ring, a wind mask or air hood, a lever press plate, a spring, a flint, a bracket, and an igniting wheel set mounted on the bracket, wherein the igniting wheel set is an igniting wheel and a “cincture wheel” that are fixed together and rotate and stop simultaneously. The conventional cincture wheel includes a central axle on which the igniting wheel is fixedly mounted. The conventional cincture wheel is positioned so that its outer perimeter is slightly higher than the igniting wheel, normally as a result of the igniting wheel being mounted coaxially with the cincture wheel, and the cincture wheel having a larger outer diameter than the outer diameter of the igniting wheel. This conventional cincture wheel typically has a toothed or a many-ridged surface, so that the user's thumb/finger may grip and rotate the cincture wheel to rotate the cincture-wheel-igniting-wheel combination. When users use ordinary strength to rotate the combined igniting wheel and cincture wheel unit (simultaneously), the igniting wheel movement relative to the flint will result in friction to generate sparks, and the purpose of igniting the lighter can be achieved when the lever press plate is depressed at the same time to release fuel. However, a simple lighter such as this cannot effectively avoid various risks caused by ignition of the lighter when a child plays with the lighter, as sparks may be fairly easily generated when the combined igniting wheel and the cincture wheel unit is rotated accidentally.

Simple Safety Lighter

One modification of this simple lighter that is currently in the marketplace is a simple lighter that is provided with a guard extending over the otherwise-exposed portion of the igniting wheel, so the user's thumb/finger must only contact and rotate the toothed/ridged cincture wheel in order to rotate the cincture wheel-igniting wheel combination. Such lighters may be called “simple safety lighters.”

As it is known that the disposable lighter is common and relatively cheap, it is impossible to incorporate expensive and complex safety devices that greatly increase the cost of the lighter. Such expensive safety devices in a disposable lighter simply would not be tolerated by the economics of the marketplace.

Double-Wheel Safety Lighters

In order to provide safe use of a disposable lighter and avoid dangers caused by accidental ignition of lighters such as the “simple safety lighter” described above, various measures have been adopted. In order to minimize the manufacturing cost of a disposable lighter with a safety ignition unit, one of the most common types of disposable safety lighters is the drive wheel type disposable safety lighter. This type of disposable lighter comprises a pair of drive wheels driving the striker wheel to rotate in order to generate sparks, wherein the drive wheels normally run idle, physically disengaged from the striker wheel, in order to prevent unwanted ignition. Such designs may be called “double drive wheel” designs or “double-wheel” designs, as it is understood that the double wheels are provided in addition to a sparking/striking wheel, for a total of three wheels. In these double-wheel prior art safety lighters, the device typically relies on the double drive wheels not easily rotating the striker wheel, and some means of the drive wheels disengaging and engaging the striker wheel must be provided. See, for example, U.S. Pat. No. 5,547,370.

Other Safety Measures:

U.S. Pat. No. 5,002,482 discloses a wheel system that has two wheels, one on each side of the striking wheel, wherein the child-resistant device relies on a relief mechanism to block the gas fuel and to prevent ignition of the lighter by pressing the safety ring downward.

U.S. Pat. No. 7,004,750 B2 discloses a striker wheel and two gear elements forming a combined unit, but with the added complexity of two driving caps at each end of the striker wheel. Each gear element comprises a gear wheel with teeth, an inner support shank, and an outer supporting shaft (all integral parts of the gear element). The inner support shanks each comprise a wheel axle that is fixed to the striker wheel, and a support wheel that has a width adapted to provide a “supporting gap” between an end surface of the striker wheel and the end (inner side) of the gear wheel. Each gear element's support wheel is smaller in diameter than its gear wheel. The two gear elements, specifically, the outer supporting shafts of the gear elements, are arranged for respectively and rotatably mounting to two supporting walls in such a manner that the combined unit (striker wheel fixed to gear elements by fixed connection between the striker wheel to the wheel axles of the two gear elements) is capable of being driven to rotate when the two gear wheels are driven to rotate.

In U.S. Pat. No. 7,004,750, encircling the combined unit at each of said support gaps, that is, encircling each of the support wheels and each of the gear wheels, are two driving caps, which each have an outer perimeter “driving ring” portion with an outer circumferential “slipping” surface. Each driving cap has a central support hole, receiving the support wheel of its respective gear element, which central support hole is slightly larger in diameter than the diameter of the support wheel. Each driving cap also has a circular driving cavity formed within the driving ring and the inner sidewall, wherein each of the driving cavities has a diameter larger than that of its respective toothed gear wheel. Thus, each driving cap is freely rotatably mounted in its respective supporting gap, and in its position “overhanging” its respective gear wheel. Still, the driving caps are arranged to engage with their respective gear wheels, by means of driving teeth in the driving cavity that engage the teeth of the gear wheel upon an adult pressing down on the driving cap. This way, the force applied by an adult will move the driving caps down relative to the gear element, engaging the cavity driving teeth with the gear wheel teeth, so as to drive the combined unit (the gear element and the striker wheel fixed together) to rotate for striking the strike wheel against the flint supported by a spring to produce sparks, thereby igniting the lighter. However, the present inventor notes that the presence of the driving cavity makes it difficult to ensure the most proper engagement between the driving caps and the gears of driving wheels, thus causing the ignition operation somewhat difficult.

Another disposable lighter, disclosed in U.S. Pat. No. 6,494,709, comprises a striker wheel coaxial with, and fixed to, two driving wheels to make a combined unit. Each of the two driving wheels has an outer circumferential toothed surface. A child resistant device is provided, wherein the safety device comprises a pair of disc-ring units (shelter ring combined, and integral, with said protection disc). The inner diameter of each shelter ring is larger than the outer diameter of the driving wheel so as to define a safety gap between an inner circumferential surface of the shelter ring, which protrudes over the driving wheel, and the circumferential teeth surface of the driving wheel. Importantly, however, the shelter ring has a width shorter than a thickness of the driving wheel, thereby defining an uncovered portion of the circumferential teeth surface of the driving wheel, which uncovered portion of the teeth surface serves as the surface contacted by the user for actuating movement of the combined unit. In other words, the uncovered portion of each driving wheel toothed surfaced serves as the “actuating edge” that is contacted by the user, and moving said actuating edge moves the driving wheel, which, due to the fixed connection between the driving wheel and the striker wheel, moves the combined unit of which the striker wheel is a part.

In order to ignite the disposable lighter of U.S. Pat. No. 6,494,709, an adult's thumb must be intentionally pressed on the shelter wheels downward until his or her thumb's surface extends through/past the safety gaps (between the shelter ring and the driving wheel) to come in contact with the uncovered portion of the teeth portion (that is, to come in contact with the “actuating edges”) of the driving wheels. By the user thus rotating the driving wheels at the actuating edges, the striker wheel is driven to be rotated to ignite the disposable lighter. The patent disclosing this lighter teaches specifically that the adult thumb will only contact the driving wheels (the uncovered actuating edges) but not the striker wheel, such that no residue on the striker wheel will stick to the adults' thumb after every ignition of the disposable lighter.

A child's thumb is relatively short, and thus not capable of contacting the uncovered edges of the driving wheels of U.S. Pat. No. 6,494,709, therefore the purpose of preventing the child from accidentally igniting the lighter is obtained. However, the present inventor notes that, since the fingers of the adults are greatly inconsistent in length, the design and manufacture of the safety gap and the “uncovered portion” of the drive wheels are of great difficulty. In addition, even if a safety gap is designed, it does not necessarily suit each adult user.

Safety has been improved in some lighters by adding relatively expensive new components. For instance, an elastic sheet controller has added to form a set of safe switches by using the recess located beneath the lever press plate of the existing simple-type igniter and on the top of the body, wherein there is a vertical plate beneath the front end of the controller (note: the plate is narrower and thinner on the upper portion and wider and thicker on the lower portion), and there is a through-hole in the plate of the controller. When in normal conditions, the controller is in a lower position, and the through hole of the upper plate is displaced with a protrusion beneath the lever press plate. By virtue of this condition, the safety feature in which gas cannot escape is achieved. However, if the controller is pushed inwardly and upwardly, then the through hole of the plate of the controller is engaged with the protrusion beneath the lever press plate, such that the controller cannot block the gas. At the time, the lever press plate is depressed together with the controller such that gas is released to ignite. However, when the lever press plate is released and moved upward, since the plate of the controller is narrower and thinner on the upper portion and wider and thicker on the lower portion, the pressing of the plate and the elastic sheet together keeps the controller in the lower position, at the time, the protrusion beneath the raised lever press plate is displaced with the through hole of the plate again, and the safety condition in which the lever press plate cannot be depressed is resumed. This improvement measure has indeed improved the safety of the igniter, but it also leads to higher design and production cost.

Whichever measures are used, there will be some drawbacks, such as increase in cost due to increase of design works, assembly and materials, higher selling price or lower profit; therefore, these measures are impractical for widespread use. The prior art proposals can increase of the cost of the lighters due to the increase of the design difficulty, assembly complexity and raw materials, and consequentially raise the price or obviously bring down the benefits, thus it is difficult to be popularized in practice.

The present invention, on the other hand, provides a simple and low-cost disposable lighter with an effective safety ignition unit, which prevents the disposable lighter from being ignited accidentally.

SUMMARY OF THE INVENTION

Aiming at solving the disadvantages of the prior art, an object of the present invention is to provide a safety lighter with a double-wheel and buffer-wheel ignition device. The safety lighter has structure that can effectively prevent the accidents caused by igniting the lighter due to misoperation and playing of children and has a low manufacturing cost that can make it popular as a disposable lighter.

The preferred embodiments of the invention comprise, as is common to disposable lighters, a lighter body and a lighter head, and the lighter head is provided with a nozzle, a flame adjusting ring, a wind mask, a bridge plate, a spring, a lighter flint, a bracket and a wheel system that may also be called a “flint wheel system”. To accomplish the above objects, the flint wheel system for the invented safety lighter is a double-wheel and buffer-wheel ignition device.

In the preferred embodiment of the invention, double rotating wheels are provided, one rotating wheel on each side of the sparking wheel that generates sparks by striking against the lighter flint, and have axle portions that connect to the sparking wheel, so that the double rotating wheels and sparking wheel rotate together on a combined axle rotatably supported in walls of the lighter head. A mechanism provided to create friction and/or bias that prevents easy rotation of the flint wheel system. Typically, said mechanism is provided by the spring that biases (pushes) the flint toward the flint wheel system; this pushing of the flint against the wheel system both makes the wheel system more difficult to turn, and, when the wheel system is turned, creates the friction between the flint and the sparking wheel that creates the spark. Other friction and/or bias mechanisms may be provided, for example, friction or bias in the rotatable connection between the wheel system and the lighter head bracket wall, but this is less preferred and would be unnecessarily complex.

A buffer wheel is received around a portion of the inner axle of one of the double rotating wheels, so that the buffer wheel is between one of the double rotating wheels and the sparking wheel. The buffer wheel further hinders rotation of the rotation wheels and sparking wheel, as it partially blocks access to the rotating wheel to which it is adjacent and, therefore, tends to prevent a user, especially a user with a smaller thumb/finger, from applying direct force on both rotating wheels at the same time. The buffer wheel normally idles freely around said portion of the inner axle, due to the buffer wheel aperture diameter being slightly larger than the diameter of said portion of the inner axle, so that a small gap exists between the aperture surface of the buffer wheel and said portion of the inner axle. In other words, the buffer wheel is slightly loose on its axle portion, and will tend to slightly wobble and/or freely spin when light to medium pressure is applied, for example, by a child. However, the gap is small, and, upon sufficient downward force on the buffer wheel, the gap will close at the region corresponding to the direction of force (typically, at the top region of said portion of the inner axle) so that said polygonal surface of the inner axle portion will mate to some extent with said aperture surface. This “mating” between the surface of said portion of the inner axle and the preferably-smooth aperture surface, comprises these surfaces being forced together so that there is gripping/friction between at least portions of the two surfaces, so that rotational force on the buffer wheel helps drive the adjacent rotating wheel.

Thus, the polygonal surface of said portion of the inner axle and the preferably-smooth aperture surface may be said to form a “port” that is open during a non-igniting configuration for safety (with little gripping/friction between the buffer wheel and the axle portion), and partially closed into an igniting configuration when appropriate adult force is intentionally applied (with greater gripping/friction between the buffer wheel and the axle portion). One may understand from this description and the drawings, that the “open” configuration may be described as the circular/cylindrical aperture surface of the buffer wheel slipping, sliding, and/or slightly bouncing past the polygonal surface of the axle portion when the buffer wheel is only lightly pressed or lightly spun by a user. One may also understand from this description and the drawings, that the “partially closed” configuration may be described as a portion of the polygonal surface of the axle portion gripping/frictionally-engaging a portion of the circular/cylindrical aperture surface when the two structures are forced together firmly. On may understand from this description and drawings that, in this “partially closed” configuration, the buffer wheel will be non-coaxial with the axle portion it surrounds, that is, slightly offset due to the firm force pressing the buffer wheel against the polygonal axle surface. The surprising combination of the preferred polygonal axle surface and the smooth circular/cylindrical aperture surface results in the surprisingly effective disengagement, and engagement, depending on whether light or moderate force is applied, for example by a child, or whether a greater force is applied, for example, by an adult.

By providing such a buffer wheel, and only providing one of them, the preferred ignition wheel device is economically manufactured with little change to any other part of the lighter. The buffer may be included in a common double-wheel system, with little if any change to the total axial length of the wheel assembly (W in FIG. 1, in the axial direction, parallel to the common axle of the flint wheel set), and, hence, little if any change to the lighter structure other than the wheels. The preferred embodiment provides an improved safety ignition wheel device by only modifying one of the double rotating wheels to cooperate with a single buffer wheel, and by fitting a buffer wheel into the space made by, and on the inner axle portion created by, the single rotating wheel modification. Preferably, there is no second buffer wheel between the plain-edge rotating wheel and the sparking wheel, and preferably there is no wheel, ring, or any other element between the plain-edge rotating wheel and the sparking wheel. The preferred embodiment is a low cost and efficient structure that can effectively prevent the accidents caused by igniting lighters due to the misoperation or playing of children.

The preferred flint wheel system double rotating wheels are a central-shaft rotating wheel (which preferably has a rough edge, such as a toothed, knurled or other non-smooth edge), and a plain-edge rotating wheel. Said rotating wheels are located on opposing sides of a sparking wheel. Preferably, the axle protruding inward from the main body of the central-shaft rotating wheel comprise two portions, one being the “intermediate axle portion” near the main body of the rotating wheel, and one being “the innermost axle portion” farther away from the main body and farthest inward toward the striking wheel. The intermediate axle portion has a diameter intermediate between the main wheel body and said innermost axle portion. The buffer wheel, located between the central-shaft rotating wheel and the sparking wheel, encircles the intermediate axle portion. The “central-shaft” rotating wheel is thus-named because it includes said intermediate axle or shaft portion that is “centrally-located” between, and is sized between the diameters of, the main wheel body of the rotating wheel and the innermost axle portion.

The central-shaft rotating wheel and the plain-edge rotating wheel are operationally coupled together and reside on two ends of the sparking wheel, with the buffer wheel generally coaxial with the two rotating wheels but not itself comprising any axle portion; thus, the buffer wheel may be considered a ring. The coupling between the two rotating wheels is done by means of axle portions contributed by each of the rotating wheels being inserted into and forming an interference/friction fit with the sparking wheel aperture, but not being attached to each other. The outer diameter of the inner axle of the plain-edge rotating wheel is sized to equal and mate with the inner diameter of the sparking wheel aperture to cause sparking wheel rotation if the plain-edge rotating wheel is rotated. Likewise, the outer diameter of the innermost axle portion of the central-shaft rotating wheel is sized to equal and mate with the inner diameter of the sparking wheel aperture to cause sparking wheel rotation if the central-shaft rotating wheel is rotated. Polygonal or irregular surfaces are used for connecting wheels of the ignition device that remain in mechanical and operative connection throughout use of the lighter, that is, the polygonal/irregular surfaces of the axle portions of the central-shaft rotating wheel and the plain-edge rotating wheel mating with the polygonal/irregular surface of the sparking wheel aperture. Preferably, said polygonal/irregular surfaces have 4-20 edges and sides, and most preferably 10-20 edges and sides, or other toothed or knurled texture.

Prior to insertion of the innermost axle portion of the central-shaft rotating wheel into the sparking wheel aperture, the buffer wheel is installed by sliding the buffer wheel over the innermost axle portion and onto the intermediate axle portion. Outer axles of the central-shaft rotating wheel and the plain-edge rotating wheel are rotatably supported (“bridge-jointed”) on the bracket of the outer lighter head, so that the joined/connected axle portions operate as a common rotating axle/shaft of the rotating wheels and the sparking wheel.

Alternative ways of forming the common rotating axle/shaft axle of the flint wheel system may be used. For example, less preferably, the axle portions of the double rotating wheels may being connected to each other inside the sparking wheel aperture as well as forming the interference/friction fit with the sparking wheel aperture. Also, less preferably, the axle connection between the central-shaft rotating wheel and the sparking wheel, and the axle connection between the plain-edge rotating wheel and the sparking wheel, may be non-fixed, and, instead, may have small gaps between the axle portions and the sparking wheel that close only when sufficient force is placed directly on the plain-edge rotating wheel and directly and/or indirectly (as described later) on the central-shaft rotating wheel. Such force would force both rotating wheels downward to close a portion of each gap, and, hence, allow the plain-edge rotating wheel and the central-shaft rotating wheel to engage/grip the sparking wheel by means of mating or substantially mating polygonal and/or irregular surfaces.

When the flint wheel system (or “wheel set”) is installed in the outer lighter head bracket wall, it is constrained from moving significantly out away from the flint, preferably by means of the outer axles of each of the two rotating wheels being rotatably received in a circular holes in the outer lighter head bracket wall. With the flint wheel system thus retained, the spring-biased engagement of the flint against the striking wheel tends to bias the sparking wheel (and therefore, the entire flint wheel set) to be difficult to rotate, and, hence, difficult to move against the flint to light the lighter. Therefore, a sufficient and effectively-directed force is required to move the flint wheel set, and the preferred embodiment is effective as a safety device because the preferred device is specially-adapted to control where and how force is applied, based on the size and strength of the user. The outer surface of the preferred plain-edge rotating wheel is smooth and comfortable to touch, but, for most people, thumb/finger contact with the plain-edge rotating wheel alone is not sufficient to rotate the entire flint wheel set, and, hence, is not sufficient to ignite the lighter. Therefore, additional contact with, and force against, the flint wheel set, other than just contact and force against the plain-edge rotating wheek, is required to rotate the flint wheel set to create a spark. The invented specially-adapted device, at least to some extent, controls access to the portions of the flint wheel system that most effectively result in flint wheel set rotation and sparking, and also provides an operative connection that is effectively engaged only by those having greater strength. An important element in this special adaptation if the single buffer wheel, which both shields one of the rotating wheels from smaller thumbs/fingers and is engageable, to itself assist in flint wheel system rotation, only by those of greater strength. Thus, people with larger thumbs/fingers and/or greater strength operate the lighter by contacting and rotating one or both of the double rotating wheels, with additional, indirect, transfer of force to one of the double rotating wheels by means of the buffer wheel.

The preferred buffer wheel is unusual in that it has a smooth inner surface that cooperates with a polygonal/irregular outer surface of the intermediate axle of the central-shaft rotating wheel. The gap between the smooth circumferential surface of the aperture of the buffer wheel and the polygon/irregular surface of the intermediate axle portion is preferably 0.08-1.2 mm, all around the circumference of the buffer wheel aperture if the buffer wheel is centered on the intermediate axle portion, and most preferably 0.1 mm. One may note that gravity may cause the buffer wheel to rest on the top of the intermediate axle portion, resulting in much of the gap appearing below the intermediate axle portion. This gap functions as a buffer, that is, providing a gap in the mechanical connection between members of the ignition device, so as to increase the difficulty of ignition, as described elsewhere in this document.

Compared with the prior art, the present invention has the following advantages: under the precondition of not changing the structure of the original simple lighter, described above in Related Art, except for changing/adding components to the flint wheel device, the invented safety lighter can improve the safety protection of the lighter. The purpose of preventing unwanted ignition and burning can be achieved in the present invention by making only simple modifications to individual components of the lighter. The invented safety lighter has convenient operation and low cost and can effectively prevent the incidents occurring when children play with lighters. Further, the invented lighter can effectively prevent the accidents caused by the unexpected rotation of the sparking wheel to generate sparks during the delivering or carrying the lighter. The safety lighter is practical and economical and the inventor believes that the lighter can be popularized in the marketplace. The invented device is produced by making a modification to the simple lighter, which is more convenient to be used by the adult and is difficult to be operated by children.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed description of the preferred, but not the only, embodiment of the invented lighter and invented flint wheel set is to be made by reference to the accompanying drawings:

FIG. 1 is the three-dimensional schematic drawing of the preferred embodiment of the invented safety lighter.

FIG. 2 is an exploded schematic view of the preferred set of the invented flint wheels of the embodiment of FIG. 1.

FIG. 3 is the schematic drawing of the set of flint wheels of FIG. 2, in partially-assembled condition, illustrating how the intermediate axle portion of the central-shaft rotating wheel is inserted into the buffer wheel to form a rotating-wheel-buffer-wheel combination.

FIG. 4 is the schematic drawing of an assembled set of the flint wheels of FIGS. 2 and 3.

FIG. 5 is the schematic drawing of attempted operation by a child of the preferred embodiment of the set of flint wheels with double-wheel and buffer-wheel ignition device, wherein the child may be able to touch both the buffer wheel and the plain-edge rotating wheel but, as will be understood from this Description, the child's thumb/finger will tend to slide off of the freely idling buffer wheel and off of the plain edge of the plain-edge rotating wheel, without providing enough force to push the buffer wheel into engagement with the axle in the buffer hole and without enough force to drive the plain-edge rotating wheel, and, thus, without enough force to rotate the flint wheel set.

FIGS. 6A and B are schematic drawings of two modes of ignition operation by an adult, with a bigger and more forceful thumb/finger. In FIG. 6A, the adult thumb/finger contacts and pushes both the buffer wheel and the plain-edge rotating wheel (as shown by the arrows on the thumb/finger), with enough force to directly rotate the plain-edge rotating wheel and indirectly rotate the central-shaft rotating wheel via rotating of the buffer wheel, thus, rotating the flint wheel set to create a spark. In FIG. 6B, the adult thumb/finger contacts and pushes the buffer wheel, the plain-edge rotating wheel, and at least to some extent also the central-shaft rotating wheel (as shown by the arrows on the thumb/finger), with enough force to directly rotate the plain-edge rotating wheel, indirectly rotate the central-shaft rotating wheel via rotating the buffer wheel, and also, at least to some extent, directly rotating the central-shaft rotating wheel, thus, rotating the flint wheel set to create a spark

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the Figures, there is shown one, but not the only, embodiment of the invented safety lighter with a double-wheel and buffer-wheel sparking device. Referring to FIG. 1, the preferred embodiment comprises conventional parts that are known in many lighters L designs, including, for example, a lighter body 1, a nozzle 6, a flame adjusting ring 4, a wind mask (not shown), a bridge plate 5, a nozzle 6, and an outer lighter head 3, a spring 7, and a lighter flint 8, and a wind mask 9. In addition to conventional parts, the lighter includes an invented set of flint ignition wheels, which preferably takes the form of set of wheels S. This set of wheels S incorporates a double-wheel and buffer-wheel sparking design that provides comfortable and safe operation, so that adults find the device convenient and pleasant to operate and children find it difficult or impossible to operation.

Referring to FIG. 1 and FIG. 2, the double-wheel and buffer-wheel set of wheels S includes two rotating wheels disposed on opposite sides of the sparking wheel, and a single buffer wheel between one of the rotating wheels and the sparking wheel. More specifically, the preferred embodiments comprises central-shaft rotating wheel 11 and plain-edge rotating wheel 13, serving as the two rotating wheels, which are attached to and drive sparking wheel 10 that is used to generate sparks by being struck against the lighter flint 8. The central-shaft rotating wheel 11 and the plain-edge rotating wheel 13 are coupled to the sparking wheel 10 at opposite ends of the sparking wheel 10 by an axle system comprising shaft/axle portions that attach directly to each other inside the sparking wheel, or that individually attach directly to the sparking wheel but do not directly attach to each other. The shaft/axle portions may stay fixed to the sparking wheel preferably only by frictional engagement inside the sparking wheel, or may alternatively or additionally fixed by adhesive or other attachment means. The axle system also comprises outer ends that extend from the set of wheels S that are rotatably received in a lighter head bracket wall system 2 that supports the set of wheels S. The buffer wheel is in the middle of (between) the central-shaft rotating wheel 11 and the sparking wheel 10, and encircles a portion of the axle system.

Preferably, the diameter of the plain-edge rotating wheel 13 inner shaft 133 equals the inner diameter 101 of the sparking wheel 10 (with slight tolerance for sliding of the two wheels together in an interference fit) and/or otherwise tightly mates with the sparking wheel 10. This makes the plain-edge rotating wheel 13 and the sparking wheel 10 rotate together.

Preferably, the innermost shaft 114 of the central-shaft rotating wheel 11 equals and/or otherwise tightly mates with the inner diameter 101 of the sparking wheel 10, so that the central-shaft rotating wheel 11. This makes the central-shaft rotating wheel 11 and the sparking wheel 10 rotate together.

Thus, multiple shaft/axle portions are coaxial with each other, extend between and connect wheels 11, 10, 13, and form a common axle on which the two rotating wheels (wheel 11 and wheel 13) and the sparking wheel 12 rotate as a single unit. The outer ends of this common axle, which are outer shaft 111 of the central-shaft rotating wheel and outer shaft 134 of the plain-edge rotating wheel, are bridge-jointed on the bracket of the outer lighter head (rotatably received in axle bores in the bracket wall 2 or by other means of rotatable support). This way, the axle portions connected and suspended in the outer lighter head are the common axle of the ignition device, rotatably supporting multiple wheels and/or rings in the confines defined by the bracket walls 2 of the lighter head 3.

The largest-diameter surface 113 of the central-shaft rotating wheel 11 is preferably provided with gear teeth, knurling, or other roughness. While a child's thumb/finger will tend not to contact this surface 113 (see FIG. 5), an adult's thumb/finger may touch this surface 113 while lighting the lighter, so that it is preferred to make this surface 113 a toothed, knurled, or otherwise gripping surface to assist in rotating of the wheel set S. The buffer wheel tends to shield the surface 113 from contact by a child's thumb/finger, even though the buffer wheel does not extend over, does not cover, and does not contact surface 113 in any way; rather, the buffer wheel shields surface 113 by being a larger diameter and immediately adjacent to the wheel's surface 113 to block access to surface 113 by small thumb/fingers that are resting/pushing on wheels 10, 12, and/or 13. The outer perimeter surface 132 of the main body of the plain-edge rotating wheel 13 is preferably smooth, so that the typical child will contact wheel 12 and 13, and wheel 12 will freely rotate and the child's skin will slide along and slip off of wheel 13. Preferably, the outer diameter of the buffer wheel 12 and the outer diameter of the main body of the plain-edge rotating wheel 13 are the same or approximately the same, while the outer diameter of the main body of the central-shaft rotating wheel 11 is slightly less than both of wheels 12 and 13, for example, 10-25 percent less and more preferably 18-22 percent less. This difference in diameters tends to shield the central-shaft rotating wheel 11 from a child's thumb/finger, but tends to expose the central-shaft rotating wheel 11 to an adult's thumb/finger. By “approximately the same”, it is meant that the outer diameter of the buffer wheel 12 is different (larger or smaller) than the outer diameter of the main body of the plain-edge rotating wheel 13 by 10% or less, and more preferably by 5% or less, of the buffer wheel 12 diameter.

A “port” is provided in that a gap is provided between the polygonal axle portion of the central-shaft rotating wheel 11 and the smooth aperture (121) of the buffer wheel 12 that is about 0.08-0.12 mm, and more preferably 0.1 mm, so that the inner diameter 121 of the buffer wheel is slightly larger than the outer diameter of the intermediate axle portion 115 of the central-shaft rotating wheel 11. Thus, the buffer wheel normally idles in operation, with a gap or slight disconnect between the buffer wheel 12 and the rotating wheel 11, so that mating of the two surfaces is not a tight engagement and is not sufficient for the buffer wheel to drive the central-shaft rotating wheel unless the user can supply a large, adult-strength, downward and rotational force to the buffer wheel. Upon attempted operation by a child, the buffer wheel smooth inner surface does not engage sufficiently with the central-shaft rotating wheel, but, upon operation by an adult, a portion of each of the smooth and the polygonal surfaces come together and this contact is sufficient to transmit force from the buffer wheel to the central-shaft rotating wheel. The combination of an adult's thumb/finger force on the plain-edge rotating wheel and on the buffer wheel (and, hence, transmitted to the central-shaft rotating wheel) is sufficient to rotate the entire flint wheel set and provide the spark for ignition. Alternatively, the combination of the adult's thumb/finger force on the plain-edge rotating wheel, on the buffer wheel, and on the main body of the central-shaft rotating wheel is sufficient to rotate the entire flint wheel set and provide the spark for ignition.

The central-shaft rotating wheel 11 consists of an outer shaft 111, an intermediate shaft 115 and an innermost shaft 114. The outer shaft 111 is bridge jointed on the bracket of the outer lighter head 3, the intermediate shaft 115 passes through the inner hole 121 of the buffer wheel 12 and the innermost shaft 114 passes through the axle hole 101 of the sparking wheel 10. The inner shaft 133 of the plain edge rotating wheel 13 is coupled in the inner hole of the other end of the sparking wheel, and the intermediate shaft 115, the innermost shaft 114 of the central-shaft rotating wheel 11, the inner shaft 133 of the plain edge rotating wheel and the axle hole 101 of the sparking wheel 10 are all provided with polygon shape.

Referring to FIG. 4, the double-wheel plus sparking wheel assembly is created preferably with interference fit and/or friction between the shafts and apertures of these wheels, connecting all of wheels 10, 11, 13 together. Buffer wheel 12 idles on the double-wheel plus sparking wheel assembly, until appropriate force is applied by an adult as described below.

The user does not have to touch the sparking wheel 10 with his/her thumb/finger, but must have sufficient force to rotate one or both of the central-shaft rotating wheel 11 or the plain-edge rotating wheel 13 so as to drive the sparking wheel 10 to rotate simultaneously in order to ignite. Thus, the device has a double-wheel function, however, as discussed further below, the buffer wheel makes it difficult for any user to apply force directly to the central-shaft rotating wheel. The buffer wheel, because it is inward relative to, and larger diameter relative to, the central-shaft rotating wheel main body surface 113, acts to shield the central-shaft rotating wheel and prevent the user's finger from directly contacting it.

If users have not enough strength to rotate the central-shaft rotating wheel 11 or the plain edge rotating wheel 13 with their thumb/finger as further describe later in this document, the buffer wheel 12 only idly rotates and the thumb/finger merely freely rotates the buffer wheel 12 rather than rotating the wheel set S. Therefore, there is no sparking and the lighter can not ignite.

FIG. 4 illustrates to best advantage the relative positions, shapes, and sizes of the various wheels in the wheel set S that make the system work well for child-proofing. One may see that the thickness of wheel 11 (axial dimension of surface 113, parallel to the axle/shafts lengths) is smaller than the thickness of wheel 13 (axial dimension of surface 132). Also, one may see that the diameter of wheel 11 (measured at surface 113) is smaller than the diameter of wheel 13 (measured at surface 132) and also smaller than the diameter of buffer wheel 12 (measured at surface 122). The smaller thickness of wheel 11 provides room between wheel 11 and sparking wheel 10 in which buffer wheel 12 can fit. The smaller diameter of wheel 11, in view of larger-diameter buffer wheel 12, maintains wheel 11 surface 113 substantially out of the way of a child's thumb/finger during attempts at ignition, without extending to cover the wheel surface 113. As may be shown in FIG. 5, the child's single thumb/finger will contact the buffer wheel surface 122 but will not normally be able to contact surface 113. This is especially true if the user is a child, as a child will not have the thumb/finger size that will be able to contact all of wheels (11, 12, 13) at once. The buffer wheel 12, therefore, acts as a barrier to prevent some users from firmly contacting and gripping both of the rotating wheels 11, 13 at the same time. Thus, a child typically cannot contact and grip at the same time the two wheels (11, 13) that are directly linked to, and therefore that drive, the sparking wheel 10.

Therefore, the only options for ignition are to contact the following with enough force and comfort to drive preferred wheel 10: 1) wheel 10 by itself (unlikely in view of the difficulty of accessing wheel 10 because of its recessed diameter and the proximity of the adjacent wheels); 2) wheel 13 by itself (contacting and rotating this wheel alone comfortably and with enough rotational forced to drive the set of wheels S is unlikely, especially in view of it being smooth); 3) wheel 11 by itself (unlikely in view of surface 113 being recessed relative to the larger-diameter, immediately-adjacent wheel 12); 4) wheel 11 and wheel 12 (contacting and rotating these two wheels alone comfortably and with enough rotational force to drive the set of wheels 10 is unlikely); 5) contacting both wheel 13 and buffer wheel 12 with child-like force (will not force buffer wheel 12 to engage wheel 12 and so will not rotate wheel set S; see FIG. 5); 6) contacting both wheel 13 and buffer wheel 12 with adult force, downward in FIG. 6A, will cause buffer wheel 12 to engage wheel 11, thus applying force to both of the double-wheels (direct force to wheel 13 and indirect force via wheel 12 to wheel 11) to rotate the wheel set S; or 7) contacting both wheel 13 and buffer wheel 12 and wheel 11 surface 113, with adult force downward in FIG. 6B, wherein such forceful contact with wheels 11, 12, and 13 (direct force to wheel 13 and direct force to wheel 11, plus assistance in driving wheel 11 by indirect force applied to buffer wheel 12) causes both double-wheels to rotate the wheel set S. Of these seven options, options 6 and 7 above are the only ones likely to be effective and convenient, and the only comfortable ones for repeated operation. Therefore, an adult will quickly learn how to operate the lighter, as the operation feels and looks somewhat similar to a conventional double-wheel ignition mechanism previously provided on safety lighters. A child will typically not be able to operate the lighter.

This preferred embodiment improves the effect of safety protection without necessarily changing the main structure of the original simple lighter and without adding any components to a conventional double-wheel ignition system other than the buffer wheel 12. The safety protection works well for child-proofing and also for preventing the lighter from accidently lighting while being carried or transported, for example, in a purse, pocket, or package. It also has the advantages of convenient operation and low cost and can effectively prevent incidents and dangers.

When a user exerts a common force (equal to the force to ignite the conventional double-wheel lighter) to try to rotate the preferred set of wheels S, the buffer wheel 12 of the set of wheels S is in idle rotating state, because the inner diameter 121 (larger than the outer diameter of the intermediate shaft 115) does not engage shaft 115. In this situation, the thumb/finger tends to spin, or simply ride along with, wheel 12 as it idles, and the thumb/finger tends to slide along the smooth surface of wheel 13 without applying significant force on wheel 13. In this situation, even if the thumb presses the bridge plate 5 down as a follow-through action of said riding or sliding along wheels 12, 13 to release the fuel, the lighter still can not be ignited, for the sparking wheel 10 (including the intermediate shaft 115) does not rotate and thus does not strike against the lighter flint to generate sparks and the lighter cannot ignite without sparks. In this way, this preferred embodiment can effectively prevent children from playing to ignite lighters or turning the sparking wheel by mistake to cause dangers.

When the user needs to obtain fire, the user can exert a relatively stronger force (which is obviously stronger than the force for igniting the simple lighter or the conventional double-wheel lighter) to turn the set of wheels S, the thumb can drive the central-shaft rotating wheel 11 (typically via engagement of buffer wheel 12 with wheel 11, and/or also direct contact with surface 113) and the plain edge rotating wheel 13, which rotates the sparking wheel 10, with enough strength to create friction between the sparking wheel and the lighter flint to generate spark. At that moment, the thumb follows-through to press the bridge plate down to release the fuel so as to ignite the lighter.

In preferred embodiments, the buffer wheel is a simple, single disk with an aperture at its center, wherein the aperture has a smooth surface and the outer surface 122 of the disk is polygonal, knurled, or otherwise rough. The buffer wheel side surfaces are preferably flat, planar, and parallel to each other, with no significant recesses. The buffer wheel preferably does not have any overhanging or axially-extending edges or perimeter rims that protrude beyond the planes of their flat and planar sides. Thus, unlike the wheel hoods or shelter wheels of the prior art wherein a perimeter ring of each hood/shelter wheel extends axially to overhang and cover an adjacent wheel, the preferred embodiment of the buffer wheel is a flat disk or flat ring without such overhanging perimeter rings.

Some preferred embodiments of the invented wheel set may be described as consisting essentially, or consisting only, of one sparking wheel, two rotating wheels operatively connected to the sparking wheel, and a single buffer wheel located between one of the two rotating wheels and the sparking wheel and circumferentially extending around an axle of the wheel set. Preferably, the buffer wheel extends circumferentially around an axle portion of the rotating wheel it is near and is a simple disk with a smooth central hole and a polygonal or otherwise roughened outer edge. By providing only one buffer wheel, minimal space is used for the buffer wheel with the surprising effect that the child-proofing works effectively as described above with only the one idling wheel, rather than two. The minimal space may be provided by simply modifying (making thinner) the thickness of the main body of the rotating wheel that the buffer wheel is near, but maintaining an axle length protruding from said rotating wheel that spaces the rotating wheel from the sparking wheel and receives the buffer wheel in that space. Said axle shape may be modified to produce an axle with two different diameter portions, that is, one portion that nearly matches the diameter of the buffer wheel central hole and one portion that closely matches but is inserteable into the hole/bore of the sparking wheel. Thus, the lighter head need not be modified from the shape, size, and width that would be required for a conventional double-wheel plus sparking wheel device, and, in most embodiments, would not need to be modified from the shape, size, and width required for the original, simple lighter. The double-wheel plus single buffer wheel design, therefore, uses minimum parts and minimum or no changes to the rest of the lighter, while maximizing safety and child-proofing.

Although this invention has been described above with reference to particular means, materials and embodiments, it is to be understood that the invention is not limited to these disclosed particulars, but extends instead to all equivalents within the broad scope of the following claims. 

1. A safety lighter with a double-wheel and buffer-wheel ignition device, the lighter comprising: a lighter body for holding fuel; and a lighter head, including a fuel nozzle, a flame-adjusting ring, an air hood, a bridge plate, a spring, a lighter flint, a bracket, and a set of flint wheels; wherein the set of flint wheels includes a central-shaft rotating wheel, a single buffer wheel, a plain-edge rotating wheel, and a sparking wheel, wherein the sparking wheel generates sparks by striking against the lighter flint: and wherein: the central-shaft rotating wheel and the single buffer wheel form a set of two wheels located on one side of the sparking wheel, and the plain-edge rotating wheel is on an opposite side of the sparking wheel; the central-shaft rotating wheel and the plain-edge rotating wheel are coupled to the sparking wheel by axle portions extending out of said central-shaft rotating wheel and said plain-edge rotating wheel to enter an axle hole of the sparking wheel; said set of flint wheels being rotatably supported by axle portions extending out from the central-shaft rotating wheel and the plain-edge rotating wheel and received in walls of said bracket of the lighter head; the outermost diameter of the central-shaft rotating wheel and the outermost diameter of the plain-edge rotating wheel are both larger than the outermost diameter of the sparking wheel; and the single buffer wheel having a central aperture receiving an axle portion of said central-shaft rotating wheel so that the single buffer wheel resides between the central-shaft rotating wheel and the sparking wheel, and wherein there is a gap between said axle portion outer surface and the central aperture so that the single buffer wheel rotates freely around said central-shaft wheel axle portion in a non-igniting position; and wherein said single buffer wheel has an outermost diameter that is greater than the outermost diameter of the central-shaft rotating wheel; so that, upon the set of flint wheels being pressed by an adult user, the adult user will contact the single buffer wheel outermost diameter and the plain-edge wheel outermost diameter, and force the buffer wheel downward to close a portion of said gap to move the buffer wheel from a non-ignition configuration into an ignition configuration wherein the buffer wheel aperture surface contacts and engages said axle portion outer surface, so that rotational force applied by the adult user on said buffer wheel and said plain-edge wheel rotates the entire set of flint wheels, including the central-shaft rotating wheel, to create friction against the flint to create a spark.
 2. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1, wherein the set of flint wheels consists only of said plain-edge rotating wheel, said central-shaft rotating wheel, said single buffer wheel, and said sparking wheel.
 3. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1, wherein the set of flint wheels comprises no wheel and no ring between the plain-edge rotating wheel and said sparking wheel.
 4. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1, wherein the gap is about 0.1 mm all the way around said axle portion of the central-shaft rotating wheel when the buffer wheel is in the non-ignition configuration.
 5. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 2, wherein the gap is about 0.1 mm all the way around said axle portion of the central-shaft
 6. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1, wherein the central-shaft rotating wheel consists of an outer axle shaft, an intermediate axle shaft and an innermost axle shaft, the outer axle shaft is rotatably supported in the bracket of the lighter head, the intermediate axle shaft is inserted through the buffer wheel, and the innermost axle shaft passes into said axle hole of the sparking wheel.
 7. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 6, wherein the intermediate axle shaft of the central-shaft rotating wheel, the innermost axle shaft of the central-shaft rotating wheel, the inner shaft of the plain-edge rotating wheel and the axle hole of the sparking wheel all have a polygon shape.
 8. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 7, wherein said polygon shape has six corners or more.
 9. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1: wherein the central-shaft rotating wheel has a disk-shaped main body; wherein the set of flint wheels has an axial dimension parallel to said axle portions extending out from the central-shaft rotating wheel and the plain-edge rotating wheel and received in walls of said bracket of the lighter head; and wherein the buffer wheel does not extend axially over said main body of the central-shaft rotating wheel, so that, upon the set of flint wheels being pressed by an adult user, the adult user will contact the single buffer wheel outermost diameter, the plain-edge wheel outermost diameter, and the outermost diameter of the main body of the central-shaft rotating wheel, so that rotational force applied by the user on said buffer wheel, said plain-edge rotating wheel, and said main body of the central-shaft rotating wheel rotates the entire set of flint wheels to create friction against the flint to create a spark.
 10. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1, wherein the central-shaft rotating wheel has a disk-shaped main body and said central-shaft rotating wheel axle portions extending from the main body, and wherein said buffer wheel is a flat disk having at its center axis said center aperture, wherein said flat disk has opposing flat, planar sides and an edge surface perpendicular to said flat, planar sides, and wherein said buffer wheel has no perimeter edge that protrudes to extend over the main body of the central-shaft wheel.
 11. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 10, wherein the main body of the central-shaft rotating wheel is thinner in axial dimension than the axial dimension of the plain-edge rotating wheel.
 12. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 11, wherein the main body of the central-shaft rotating wheel and the buffer wheel each have toothed outermost perimeter surfaces, and the plain-edge rotating wheel has a smooth outermost perimeter surface with no teeth.
 13. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1, wherein the set of flint wheels includes no wheel and no ring between said plain-edge rotating wheel and the sparking wheel, and wherein the total axial length of the portion of the set of flint wheels that is received between said walls of the bracket is the sum of the axial lengths of a main body of said central-shaft rotating wheel, said buffer wheel, said sparking wheel, and a main body of said plain-edge rotating wheel.
 14. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 1, wherein the coupling of the central-shaft rotating wheel and the plain-edge rotating wheel to the sparking wheel are fixed connections that allow no relative movement between the central-shaft rotating wheel and the sparking wheel, and allow no relative movement between the plain-edge rotating wheel and the sparking wheel.
 15. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 14, wherein the largest diameter wheels of the set of flint wheels are the buffer wheel and the plain-edge rotating wheel, and said central-shaft rotating wheel is smaller in diameter and outward from the sparking wheel relative to the buffer wheel, so that the central-shaft rotating wheel is rotated only by the buffer wheel entering said igniting configuration of engagement with the central-shaft rotating wheel.
 16. The safety lighter with the double-wheel and buffer wheel ignition device according to claim 14, wherein the largest diameter wheels of the set of flint wheels are the buffer wheel and the plain-edge rotating wheel, and said central-shaft rotating wheel is smaller in diameter and outward from the sparking wheel relative to the buffer wheel, so that the central-shaft rotating wheel is rotated only by the buffer wheel entering said igniting configuration of engagement with the central-shaft rotating wheel and by contact by a user with all of said plain-edge rotating wheel, said central-shaft rotating wheel and said plain-edge rotating wheel.
 17. A safety lighter with a double-wheel and buffer-wheel ignition device, the lighter comprising: a lighter body for holding fuel, a lighter head, including a fuel nozzle, a flame-adjusting ring, an air hood, a bridge plate, a spring, a lighter flint, a bracket, and a set of flint wheels, wherein the set of flint wheels consists essentially of a central-shaft rotating wheel, a single buffer wheel, a plain-edge rotating wheel, and a sparking wheel, wherein the sparking wheel generates sparks by striking against the lighter flint; and wherein: the central-shaft rotating wheel and the single buffer wheel form a set of two wheels located on one side of the sparking wheel, and the plain-edge rotating wheel is on an opposite side of the sparking wheel; the central-shaft rotating wheel and the plain-edge rotating wheel are coupled to the sparking wheel by axle portions extending out of said central-shaft rotating wheel and said plain-edge rotating wheel to enter an axle hole of the sparking wheel; said set of flint wheels are rotatably supported by axle portions extending out from the central-shaft rotating wheel and the plain-edge rotating wheel that are received in walls of said bracket of the lighter head; the single buffer wheel having a smooth central aperture receiving a polygonal axle portion of said central-shaft rotating wheel so that the single buffer wheel resides between the central-shaft rotating wheel and the sparking wheel, and wherein there is a gap between the polygonal axle portion and the smooth central aperture, so that the single buffer wheel rotates freely around said central-shaft wheel axle portion in a non-igniting position until said gap is forced closed into an igniting position wherein the polygonal axle portion engages the smooth central aperture; the outermost diameters of the central-shaft rotating wheel, the plain-edge rotating wheel, and the buffer wheel all being larger than the outermost diameter of the sparking wheel, the outermost diameters of the buffer wheel and the plain-edge rotating wheel being approximately the same, and the outermost diameter of the central-shaft rotating wheel being 18-22 percent less than the outermost diameter of the buffer wheel; and the central-shaft rotating wheel and the buffer wheel having toothed or knurled outer perimeter surfaces and the plain-edge rotating wheel having a smooth outer perimeter surface; so that the safety lighter is adapted to not ignite when the set of flint wheels is pressed by a child, because the child touches only the single buffer wheel outermost diameter and the plain-edge wheel outermost diameter, and does not force the buffer wheel to engage sufficiently with said polygonal axle portion, so that the sparking wheel does not rotate; and so that the safety lighter is adapted to ignite when the set of wheels is pressed by an adult, because the adult touches three wheels which are the single buffer wheel, the outermost diameter of the central-shaft rotating wheel, and the outermost diameter of the pain-edge rotating wheel, pressing the single buffer wheel outermost diameter with enough force that the buffer wheel engages the polygonal axle portion to assist in driving the central-shaft rotating wheel, so that and the sparking wheel does rotate to create friction against the flint to create a spark.
 18. The method of operating a safety lighter comprising: providing a safety lighter with a double-wheel and buffer-wheel ignition device, the lighter comprising a lighter body for holding fuel, a lighter head, including a fuel nozzle, a flame-adjusting ring, an air hood, a bridge plate, a spring, a lighter flint, a bracket, and a set of flint wheels consisting essentially of a central-shaft rotating wheel, a single buffer wheel, a plain-edge rotating wheel, and a sparking wheel; wherein the central-shaft rotating wheel and the single buffer wheel form a set of two wheels located on one side of the sparking wheel, and the plain-edge rotating wheel is on an opposite side of the sparking wheel; wherein the central-shaft rotating wheel and the plain-edge rotating wheel are coupled to the sparking wheel by axle portions extending out of said central-shaft rotating wheel and said plain-edge rotating wheel to enter an axle hole of the sparking wheel, and said set of flint wheels are rotatably supported by axle portions extending out from the central-shaft rotating wheel and the plain-edge rotating wheel that are received in walls of said bracket of the lighter head; wherein the single buffer wheel has a smooth central aperture receiving a polygonal axle portion of said central-shaft rotating wheel so that the single buffer wheel resides between the central-shaft rotating wheel and the sparking wheel, and wherein there is a gap between the polygonal axle portion and the smooth central aperture; wherein the outermost diameters of the central-shaft rotating wheel, the plain-edge rotating wheel, and the buffer wheel all are larger than the outermost diameter of the sparking wheel, the outermost diameters of the buffer wheel and the plain-edge rotating wheel being approximately the same, and the outermost diameter of the central-shaft rotating wheel being 10-25 percent less than the outermost diameter of the buffer wheel; and wherein the central-shaft rotating wheel and the buffer wheel have toothed or knurled outer perimeter surfaces and the plain-edge rotating wheel having a smooth outer perimeter surface; the method further comprising: in a child-use safety mode, pressing by a child's thumb/finger on only the buffer wheel and the plain-edge rotating wheel with mild force so that said gap is not closed, the single buffer wheel rotates freely around said central-shaft wheel axle portion, and wherein the child's thumb/finger slides off the plain-edge rotating wheel, so that the sparking wheel is not rotated and no spark is creates; and in an adult-use operation mode, pressing by an adult's thumb/finger on three wheels that are the buffer wheel, the plain-edge rotating wheel, and the central-shaft rotating wheel, with said pressing of the buffer wheel being strong enough to close said gap so that the polygonal axle portion engages the smooth aperture of the buffer wheel, so that the pressing on the three wheels forces the sparking wheel to rotate against the flint to create a spark. 